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GHSA-94rc-cqvm-m4pw

MediumCVSS 6.6 / 10
Published Mar 3, 2026·Last modified Mar 4, 2026
Affected Components(0)

No affected components available

Description

There is an authenticated admin RCE in Craft CMS 5.8.21 via Server-Side Template Injection using the create() Twig function combined with a Symfony Process gadget chain.

This bypasses the fix implemented for CVE-2025-57811 (patched in 5.8.7).

Required Permissions

  • Administrator permissions or access to System Messages utility
  • allowAdminChanges enabled in production (against our security recommendations) or access to System Messages utility

Vulnerability Details

The create() Twig function exposes Craft::createObject(), which allows instantiation of arbitrary PHP classes with constructor arguments. Combined with the bundled symfony/process dependency, this enables RCE.

Attack Vector

Admin panel → Settings → Entry Types → Title Format field

Proof of Concept Payload

{% set p = create("Symfony\\Component\\Process\\Process", [["id"]])
%}{{ p.mustRun.getOutput }}

Steps to Reproduce

  1. Log in as admin
  2. Navigate to Settings → Entry Types
  3. Edit any entry type’s "Title Format" field
  4. Insert the payload above
  5. Create/edit an entry of that type
  6. Command executes, output appears in entry title

Impact

  • Authenticated Remote Code Execution
  • Runs as web server user (root in default Docker setup)
  • Full server compromise

Root Cause

Craft::createObject() allows the instantiation of any class, including Symfony\Component\Process\Process, which executes shell commands.

Suggested Fix

  • Blocklist dangerous classes in createObject() when called from Twig
  • Or remove/restrict the create() Twig function
  • Or validate class names against an allowlist

Resources

https://github.com/craftcms/cms/commit/e31e50849ad71638e11ea55fbd1ed90ae8f8f6e0

Risk Scores
Base Score
6.6

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
4.8

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.56%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Medium severity
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